The present invention relates generally to a tilt-trim subsystem assembly for marine propulsion devices and, more particularly, to a shielded tilt-trim subsystem assembly for a stern drive propulsion system.
In marine propulsion devices, it is common to have hydraulic cylinder/piston assemblies located externally of the boat for effecting pivotal movement of the propulsion unit relative to its mounting bracket. For example, in marine propulsion devices of the stern drive or inboard/outboard type, it is common to have hydraulic cylinder/piston assemblies connected between the gimbal ring and the propulsion unit to tilt the propulsion unit relative to the gimbal ring. In other types of marine propulsion devices, such as outboard motors, it is known to have hydraulic cylinder/piston assemblies connected between the mounting bracket and the propulsion unit to steer and/or tilt the propulsion unit relative to the mounting bracket.
In many of these marine propulsion devices having hydraulic assemblies located externally of the boat, means are provided for supplying hydraulic fluid to the hydraulic assemblies from a source of fluid inside the boat. The source of fluid may be connected to a hydraulic circuit also located inside the boat that pressurizes and distributes the hydraulic fluid through a manifold interconnecting respective hydraulic lines to the respective hydraulic cylinder assemblies outside the boat. The hydraulic circuit typically includes a pressure pump and an electric motor coupled to drive the pump. This configuration generally presents several issues. One issue is whether to run the hydraulic lines over the transom or through the transom and, if through the transom, how to seal the opening through which the hydraulic lines pass. Another issue is how to protect the portions of the hydraulic lines extending externally of the transom.
For example, the hydraulic lines may be exposed to a relatively harsh external environment, such as ocean salt water, damaging ultra-violet sunrays and other conditions that may promote galvanic corrosion or deterioration of the line material. Any deterioration of the lines may be further aggravated due to the bending that the lines may be subjected to as the propulsion unit is tilted upwardly and downwardly and/or a steered left and right. This may lead to leaks and a relatively short hydraulic line life. Further, these tilt/drive subsystems can often consume valuable room in the interior of the boat and/or require additional holding fixtures. Moreover, additional labor costs are often associated with installing the subsystem on the boat floor or transom.
Known tilt-trim subsystems use an intricate external assembly including separate tilt and trim cylinders to provide the tilt and trim functions to an outboard propulsion unit that may somewhat alleviate some of the above-discussed issues that often develop in outboard units. Unfortunately, these subsystems do not adequately overcome any of the aforementioned issues as may be encountered in boats using a stern drive propulsion system.
Therefore, it is desirable to design a tilt-trim subsystem assembly that, with a lesser number of components, provides tilt and trim to a stern drive propulsion system that is not subject to the foregoing problems and that can be easily installed either as a replacement kit or as part of an original installation. The increased reliability of the tilt-trim subsystem of the present invention and its ease of service are likely to result in enhanced durability at a lower cost.
Generally speaking, the present invention fulfills the foregoing needs by providing a stern drive system having an outdrive generally disposed downstream relative to water flow aft a transom of the boat. The outdrive is configured to be rotated about a generally horizontal axis to impart a desired trim or tilt to the drive system. A gimbal unit has means for pivotally receiving a first anchor pin. A tilt-trim subsystem assembly is affixed to the outdrive. The tilt-trim assembly has one respective end thereof configured to pivotally receive a second anchor pin supported by the outdrive. The assembly includes at least one cylinder having one end thereof connected to the first anchor pin such that when the cylinder is actuated by a hydraulic or electro-mechanical circuit therein the outdrive and the tilt-trim subsystem assembly are rotated about the generally horizontal axis during tilt-trim maneuvers. A housing is configured to shield the tilt-trim assembly. In one aspect thereof, the outdrive may be configured within the footprint of the housing to avoid resistance to water flow. In another aspect thereof, the housing is configured to conceal the tilt-trim assembly.
The present invention further fulfills the foregoing needs by providing a tilt-trim subsystem assembly affixed to an outdrive of a stern drive that may be supported by a gimbal unit and may be configured to rotate about a predetermined axis to impart a desired trim or tilt to the drive system. The tilt-trim assembly has one respective end thereof configured to pivotally receive one anchor pin supported by the outdrive. The assembly includes one or more cylinders having one end thereof pivotally connected to another anchor pin so that when the cylinder is actuated, the outdrive and the tilt-trim subsystem assembly are jointly rotated about the predetermined axis. The assembly further includes a hydraulic circuit for actuating the at least one cylinder therein. The tilt-trim assembly is mounted to a base for receiving a housing. The base is scalingly connected to a flange extending at the lower end of the housing to prevent entry of moisture therethrough.